Machine for honing doctor blades



u y 30, 1963 T. K. ALLISON 3,099,111

MACHINE FOR nonmc DOCTOR BLADES 3 Sheets-Sheet 1 Filed. April 12, 1961 INVENTOR. 75m; K/Z z/mv BY M; 4/4,

y 1953 1'. K. ALLISON 3,099,111

MACHINE FOR HONING DOCTOR BLADES Filed April 12, 1961 3 Sheets-Sheet 2 INV EN TOR. 72 0444: A1 fizz/my ly 30, 1963 T. K. ALLISON 3,099,111

MACHINE FOR HONING DOCTOR BLADES Filed April 12, 1961 3 Sheets-Sheet 3 7! mmvron. 7 /4014! Kill/1a United States Patent F 3,999,111 l'tiAC FGR HUNING DOCTOR BLADES Thomas K. Allison, 5963 Camden Ave, Moorestown, NJ. lFiled Apr. 12, 1961, item No. 118,478 9 Claims. (Cl. 51-3) The present invention relates to a machine for lapping or honing doctor blades.

In tgravure or intaglio printing, particularly in rotogravure printing, a doctor blade is frequently employed to wipe the ink or printing fluid from the surface of the engraving roll or the like. In order to obtain a good grade of impression and avoid smearing, the doctor blade should wipe the surface cleanly. To this end, the edge of the doctor blade should be sharp and straight, and in good registry and contact with the cylindrical surface of the roll as the roll rotates against the blade, which is normally held fixed. Gravure cylinders or plates are often copper plated with a thin, for example, .0003", layer of chromium. The of blade pressure consistent with a good wiping action is desirable for substantial cylinder life. Excess pressure due to improperly configured blades is a major source of cylinder or plate wear. To secure a proper wiping action, the edge of the doctor blade is ground or honed at a selected angle to the surface of the blade, which usually comes in a sheet-like form, and the edge is then applied to the roller at a selected angle. The blade stock may be Swedish steel .95 carbon, 50-55 Rockwell C, .006" to 0.010" steel ribbon purchased in coil dorm. The angle to which the edge is ground or lapped and the angle of application of the blade and its edge to the roller are difierent depending on different factors, for example, the viscosity of the ink, whether half-tone reproduction is sought or not, the nature of the plate (i.e., the surface of the cylindrical roll), the material and construction of the blade, and the like. For example, in many modern engravure presses, provision is made for inserting the gravure or intaglio press doctor blade with the plane of the blade applied at any desired angle within a range of angles to the engraved roll. The desired angle of the edge, by present practice, is secured by grinding or polishing the edge by hand, while the blade is out of the machine. After a certain amount of use, sometimes because of inequalities on the engraved or etched surface of the plate, sometimes because wear removes the edge and the desired wiping action is lost, or sometimes for both reasons, the doctor blade should be re-ground. Also, the new blade must have an edge prepared.

Hand grinding of the doctor blade, even with the use of a jig or the like, is tedious, and often not as accurate as desired. Sometimes the blade edge, because of the lack of accuracy, fails to provide a sufficiently high degree of continuous, close contact to the roller, and also fails to give a desired long wear which could be secured with a more accurately prepared edge.

It is an object of the present invention to provide a machine for the grinding and lapping of doctor blades.

It is another object of the invention to provide doctor blades having improved edges.

A further object of the invention is to facilitate the preparation of doctor blades, both originally and for their re-use.

According to the invention, there are provided a mounting to receive a doctor blade mounted in its holder, which is to have an edge applied thereto, a grinder arranged to traverse the length of the blade, and a lapping or honing cylinder rotatable around its own axis for applying a new, lapped edge on the doctor blade. The mounting for the blade is rotatable around an axis parallel to the direction of traverse of the grinder, and parallel to the axis of the lapping cylinder. In its preferred form, the grinder is Efiddj ll Patented July 30, 1963 ice mounted to be positioned nearer or farther from the doctor blade in minute increments as it traverses, in order to remove any desired amount of edge from the doctor blade preparatory to applying a new edge. Also, in the preferred form of the machine, the lapping cylinder is arranged to oscillate axially as it rotates. An important feature of the machine is that the lapping cylinder may be positioned to put an edge of desired angle on the doctor blade, and for that purpose it is preferably arranged on a U frame which may be rocked to the desired position by an indexed cam. In operation, the doctor blade is fixed in the mount therefor and the mount rotated to bring the edge into opposition to the grinder. The grinder then traverses to remove a desired amount of the old edge, leaving a temporary edge which is trued to the base of the doctor blade and its holder at right angles to the sheet of the blade. 'Ilhe amount is then rotated to bring the blade against the lapping or honing cylinder at the desired angle, and the new, sharp and true edge is then applied at the proper, desired angle by adjustment of the abovementioned indexing cam.

The foregoing and other objects, advantages, and novel features of the invention will be more fully apparent firom the following description when read in connection with the accompanying drawing, in which:

' FIG. 1 is a schematic line drawing illustrating the fashion in which a sharpened, trued doctor blade rides against an engraved cylinder;

FIG. 2 is a schematic line drawing illustrating, in exaggerated fashion, some of the efi'ects of wear on the doctor blade;

FIG. 3 is a perspective view of .a machine embodying the invention with cabinet removed illustrating different operating positions;

FIG. 4 is a reduced, line drawing of the machine in its cabinet;

'FIG. 5 is a perspective view showing some of the operating parts of the machine of FIG. 3 without its mount;

FIG. 6 is a detailed, enlarged view of a mechanism for adjusting the grinder spacing to the blade holder;

FIG. 7 is a sectional view of a portion of an elongated U-i'rame for mounting the honing Wheel illustrating how the honing wheel is caused to stroke as its rotates;

FIG. 8 is a sectional view taken along line 8-8 of FIG. 7;

FIG. 9 is an enlarged sectional view of a cam arrangement for selecting the position of the U frame tfior honing the doctor blade at a selected angle.

' In the drawing, like reference characters refer to like parts.

I. INTRODUCTION FIG. 1 illustrates a desirable working edge 11 on a doctor blade 10. The edge 11 bears against a photoengraved cylinder 12 or the like. The blade itself is a sheet of fine steel, for example, Swedish steel, quite flexible and having two opposed major parallel surfaces 10a and 10b, practically parallel to each other. A typical blade or steel 10 may be from five to ten mils (thousandths of an inch) thick between the surfaces 19a and 1%. The length of the blade and of its working edge 11 may be, typically, three feet or more in length. The blade 10 has an edge 13 opposite the sharpened or working edge 11. These two edges 11 and 13 are normally parallel to each other. The blade '10 is held in a blade holder 14 comprising a main bar 15, a secondary bar 117 and a back-up bar 16. Thedoctor blade 10 is clasped between the main bar 15 and the secondary ban-J16 with the rear edge 13 resting against a ledge 15a on the main bar .15. This rear edge 13 is, by the ledge 15a, held fixed in relation to the rear edge 15b of the main bar 15, and thus the working edge 11 is also held fixed in relation to the rear edge 15b. A back-up bar 17 is bolted or otherwise fastened to the main bar 15 to help stifien the blade as it bears against a cylinder. The back-up bar 16 is fastened to a chamfered surface 150 to bear against a back-up blade 1-8 under what we may call the upper surface 16b of the blade 19. The face of the back-up bar 17 hearing against the back-up blade 18 is chamfered also to support and reinforce the blade 10 against flexure, the backup blade 18 being of a cheaper steel than the thin doctor blade 10 and helping to stiffen and prevent excess flexure of the thin doctor blade.

In use, the bar 10 is held in a press to engage the edge 11 of the doctor blade 1% against the cylinder 1-2. Geometrically, the line of contact may be described as along a line element of the cylindrical surface. Usually the plane or surface of the blade 10, which we may define as the under surface 10a, is held coincident with a radial plane of the cylinder 12 at the contact line for a so-called sharp wipe, and at an acute angle to a radial plane through the line of contact and toward the direction of an approaching rotating point on the cylinder, for a so-called normal wipe, and a still larger angle in the same direction for the so-called flat wipe. The angle of wipe seldom exceeds 45. The doctor blade 10 and working edge 11 are pressure loaded by suitable means (not shown), such as springs, or pneumatic loading, against the cylinder 12.

The doctor blade edge 11 is initially sharpened to pre sent a sharp line terminating the lower surface 10a. For example, an edge 11 may be formed by providing a 45 chamfer from the upper side 101;, so that the lower side 16a simply terminates abruptly along a line of that latter surface. As the cylinder rotates with the edge and lower side 16a so terminated facing the oncoming elements of the cylinder 12, the ink is wiped clean from the surface, substantially, except for engraved portions to which it clings in known manner. As the cylinder rotates, the working edge 11 wears, becoming dull and approaching a shape conforming to the shape of the cylinder, but which is substantially planar and at right angles to the major surfaces 10a and 19b, as in FIG. 3. This wear reduces the sharpness of contact, as known, and hence reduces the wiping action. Probably the wiping action depends on the force per square unit area of contact, and the uniformity of that force, along the line of contact of the edge 1 1 and the cylinder 12. As the edge wears, the area bearing against the cylinder increases, the total loading remains about the same, and, consequently, the force per square unit area decreases. Moreover, engraved areas cause greater wear than non-engraved areas, as a rule. Thus, if the cylinder is not uniformly engraved, and it seldom, if ever, is, the result is uneven wear along the length of the blade 19, which reduces contact in spots.

Formerly, the blade 10 was removed, and a new edge fashioned by hand, as by stoning the edge 11-1 to refashion the 45 charnfer. However, the present machine performs the sharpening with greater accuracy, ease, and celerity than by hand or by a jig or the like. It is also desirable, before applying the new edge, to remove all or at least some part of the old, worn edge to insure the removal of high spots and that the new working edge 11 is parallel to the rear surface b of the holder, being trued to that rear surface, because in the press that rear surface is used to index the blade.

II. THE MACHINE A. General With reference to FIGS. 3 and 5, I provide a grinder assembly'20 which traverses the length of the blade a selected number of times for grinding, a mounting 21 for the blade and the blade holder, and a honing or lapping wheel assembly 22. These areall suitably mounted in a frame'23 which may be finished off with a cabinet.

4 B. T he Grinder Assembly The grinder assembly 2%) includes a platform 24 on which are mounted an A.C. (alternating current) motor 25 and a grinding wheel 26 belt driven from the motor 25. The platform 24 rides upon a keyed shaft or way 27 having a key 28. The platform 24 is connected by struts 30 to a plate 3 1 keyed to the key 23.

The keyed way 27 is held substantially horizontally by an arrangement which includes, at each end of the way, a lead screw 32'journalled in the sides of the frame 23. The side lead screws 32 are each driven by a worm gear 33 which are driven, in turn, by a common shaft 34, and the latter by another gearing 35 wihch may be turned manually by a control 36 at the front of the frame 23 and external to the cabinet. The lead screws 32 are parallel to each other and horizontal. Thus the key-way 27 may be moved forward, toward the front of the cabinet and frame 23 or back-ward within a selected range by turning the manual control 36. The control 36 may also be driven from a pawl and ratchet arrangement 1th), the ratchet wheel 101 of which is advanced by a pawl 102 actuated by a relay 103 once for each electrical pulse received by the relay.

A reversible motor .165 (FIG. 6) is attached to one side of the cabinet to drive, by an arrangement of belts and pulleys 106, a ball bearing lead screw 39 in one direction or the other. The lead screw 39 is mounted on the frame 23 under the key-Way 27 and with the axes of the ball-bearing lead screw 39 and of the key-way 27 parallel. A travelling, ball-bearing actuated nut 107 rides on the lead screw 39. The nut 167 is rigidly connectedto a plate 31 and the platform 24. The ball-bearing lead screw 39 then causes the platform 24 and the grinding wheel to traverse in one direction or the other along the key-way 27 depending on the direction of rotation of the reversible motor 105.

Back of the key-way 27 are mounted in the frame 33 a pair of bars 49 approximately parallel to the axis of the key-way 27, one bar 49 over the other. A pair of switch mounting plates 41 are each shaped to grasp both bars and to be fixed at a desired position, side-to-side, by a set nut 42 threaded in each plate 41 tobear against the upper bar 40. Each plate 41 carries a limit switch facing the key-way 27. Each limit switch carries a striker arm 44 which actuates the switch and an over-run wheel 45. A striker 46 is mounted on the platform 24 and has a backward reach great enough to strike the striker arms 44 from any position within the forward or backward range of the key-way 27.

C. The Blade Holder Mounting The blade holder mounting 21 includes a shaft 50 journalled in the sides of the frame 23. A gear 51 is set on the shaft 50 and turned by a Worm 52 operated by a vertical axis, manually turned wheel 53 pinned in the frame 23. On the shaft 5% are mounted clamps 54 spaced to receive between their jaws a doctor blade holder 14. The back surface 15b of the holder 14 is rested against a flat surface 56a of the shaft 55). The key-way 27 is dressed to the shaft surface 50a so that, as the grinder wheel 26 traverses from end to end of the key-Way 27 when the shaft 56 has its surface 56a directly facing the grinding wheel 26, the distance from the grinding contact point of the wheel 26 to surface 5% remains the same, preferably within a mil or two. In short, the line of traverse of the grinding wheel 26 is parallel to the surface 50a and the axis of the shaft 59.

The axis of the grinding wheel 26 is canted, though remaining in a horizontal plane, through an angle of 10 to 15 or so, so that only one edge or side of the grinding wheel 26 is active and bears against the edge 14 of the doctor blade 10 as the latter is having its old edge removed. By means of the clamps 54 a stop bar 55 is arranged in the frame 23 so that when the doctor blade holder 14 clamped by the clamps 54 is turned by rotating handwheel 53 to present the working edge 11 of the doctor blade to the grinding wheel 26 (clockwise as viewed in FIG. 3), the holder 14 and 'blade are stopped so that the grinding wheel 26, in its traverse, grinds an edge substantially at right angles to the plane or surface of the doctor blade 10.

To facilitate mounting the blade holder 14, I provide within the shaft 50 a rack and pinion arrangement (not shown), the pinion of which is operated by a lever, 92 pinned through the front of the shaft 50, and readily available to an operator. When the lever is turned clockwise from the position shown in FIG. 1, the rack slides within the shaft 50 toward the'left as viewed in that figure. The rack is provided further with two inclined surfaces about equidistant from the ends of the shaft 50 and in position to underlie both sides of the shortest bar which may be applied. A pair of lift pins extend up from the shaft 50 riding through holes provided therefor in the top of the shaft 50.

The blade holder 14 is easily mounted by using this arrangement, which helps prevent pinching of the fingers and at the same time insures that the holder 14 will not drop against or damage the indexing top surface of the shaft 50. When the lever 91 is used to move the rack toward the left, the lift pins ride up the inclined surfaces to extend above the indexing surface 50a. The holder 14 is placed on the lift pins, which support the holder 14 far enough above the indexing surface 50a to afford finger space between that surface and the holder when laying the holder 14 on the lift pins. After that, the lever 91 is turned to move the rack to the right, which may be done gradually, to withdraw the lift pins 94 within the shaft 50 as they slide on the inclined surfaces. The back surface 151) of the blade holder 14 now seats against the indexing surface 58a. The clamps 54 can now be tightened, and the blade holder 14, is in place in the machine. To remove the blade holder 14, the process is reversed, that is, the clamps 54 loosened, lever 53 operated to raise the lift pins, which affords finger room for easily lifting the blade holder 14 from the machine.

D. The Honing Wheel The honing or lapping wheel 22 is mounted in a pair of nylon bearings 60, which may afford the open, half cylindrical cups as shown for receiving the shaft ends 61 which hold the lapping or honing wheel 22. These bearings 60 are mounted on either end of the uprights 62 of an elongated U-frame 63 (see FIG. 3). The uprights 62 are journalled with pins, as at 64, into the sides of the machine frame 23. Near the center of the cross-member 65 of the U-frame 63 is mounted a cam-follower 66 which faces the front of the frame 23. In the frame 23 is mounted a cam 67 turned by a pin 68 which may extend through the front of the cabinet. A hand wheel 71 may be marked by scale divisions cooperating with an index marker on the cabinet for calibration as noted hereinafter. As the cam is turned, it rocks the frame by moving cross-member 65 forward or allowing it to move back. The position of the cam therefore controls the angle at which the edge 11 of the blade it bears against the honing wheel 22. A restoring force maybe provided by a spring The honing wheel 22 may be made of any suitably hard abrasive surfaced material. For example, I find it convenient to use a wheel of aluminum wrapped with an abrasive cioth of fineness No. 400 or No. 320. The cloth may be wrapped around the cylinder with a small pitch to leave a slight space, say one-half or one-quarter inch between wraps, to insure no overlap, and afiixed to the cylinder with any suitable adhesive or, for example, any suitable pressure sensitive double faced adhesive tape. Scotch brand masking tape No. 202 has been used.

The honing wheel 22 is driven by a motor 80 having aifixed to its shaft a drive member 81 carrying a pair of posts 82. (See FIGS. 7 and 8.) Between the posts 82 rides cam follower 83. Cam follower 83 follows a cam surface 84a of a cam 84 fixed to the motor 81 housing. The cam follower then is driven by one of the posts 82 circumferentially about the motor shaft and slides radially of the motor shaft between them as it follows the cam surface 84a which may be a plane at an angle other than 90 to the shaft axis of motor 81. As the cam follower 83 revolves about, its oscillates along this axis and rotates a shaft 85 pinned with an internally fitted pin to the shaft of motor 81 on one end, and at the other end spring loaded against a compressed spring into the open end of a tube 851: fastened to one of the uprights 62. The spring insures that the cam follower is always urged against the cam surface 84a. On shaft 85 is a gear 86 in mesh with a gear 87 slip-mounted on a shaft 83 fixed to upright member 62. The gear 87 is, in turn, in mesh with a gear 89 mounted to one of the shaft ends 61. Annular plates 87a on each side of and surrounding the gear teeth of gear 87 enclose the teeth of the gears 86 and 89 in mesh with it. Consequently, as motor 81 turns its shaft, gear 86 turns and also oscillates axially, and the gears 87 and 89 and the honing cylinder 22 also are driven to rotate about their respective axes and oscillate axially.

As a result of this arrangement, when the honing wheel motor is operated, the lapping wheel 22 is driven to rotate in a clockwise direction as viewed in FIG. 2, and at the same time oscillates in its nylon bearing with a stroke which depends on the angle of the cam 84 with the axis of motor 81. For example, a three-quarter inch stroke was found suitable and satisfactory in one machine.

E. Operation In summary, in operating the machine, a doctor blade 10 in its holder 14 is set into the blade holder mounting, first operating the lever 92 to operate the lift pins, and after the blade holder 14 rests on these lift pins, then operating the lever to retract them. The blade holder 14- is then tightened in place with clamps 54. The wheel 53 is operated to turn the clamped blade holder 14 perpendicularly to the line of travel of the grinding wheel 26. The wheel 36 is operated to bring the grinding wheel toward the doctor blade to remove the desired amount. Not shown, because it is not part of the invention, is a circuit whereby the desired number of passes of the doctor blade maybe set :on a dial. When the switch (not shown) for starting the grinding wheel is thrown, the wheel malees a complete pass it actuates one of the limit switches 41. If desired, the switch may open the motor circuit. However, by the circuit mentioned, the number of passes are counted, each throw of the switch causing a reversal of the motor connections to reverse [the direction of rotation of the motor shaft of motor @105. With each reversal of direction of rotation, an electrical impulse is applied to relay 103 which steps the ratchet 101 to move the grinder a thousandth inch or less closer to the doctor blade removing a slight bit more of the edge. If desired, the electrical circuit need not be used for this purpose, but after each pass, the hand wheel 36, used for the initial adjustment, may be used to advance the grinding wheel 26. After any desired amount is removed from the doctor blade 10 edge, the motor 25 for the grinder and the motor M5 for the traverse lead screw 39 are stopped. The wheel 35 is operated to turn the doctor blade against the honing wheel 22, with the blade holder horizontal. The position of the honing wheel is adjusted by the indexed wheel 114. The switch (not shown) for the honing wheel motor 81 is now thrown. The honing wheel strokes and hones the doctor blade until the desired angle of edge is created, and the doctor blade 10 may .be removed, using the lift pins, in the reverse of the manner in which it was inserted.

The arrangement of the bearings 60 permits the holding wheel 22 to be replaced merely by lifting out the cylinder 22 and dropping in another, using the same or same size gearing 89. By this means, the size of the cylinder may also be readily changed for a further change of the angle honed on the applied blade. When the blade is pressed against the honing wheel 22, it is pressed away from the back-up blade 18 and flexes substantially. This flexure (not indicated in the drawings) is considered in calculating the angle of edge honed on the blade, and also causesthe edge to be slightly hollow ground, making a superior edge.

What is claimed is:

l. A machine for honing a doctor blade having a longitudinal axis comprising a mounting for holding said blade, a honing wheel, means for mounting said honing wheel for rotation about an axis parallel to said first mentioned axis, means for driving said honing wheel simultaneously for rotation about its axis and for a stroking motion back and forth in a direction parallel to its said axis, said honing wheel mounting means comprising a U-frame across the upright bars of which said honing wheel is mounted and a means for selectively positioning said U-frame rotatably about an axis parallel to said axes to provide a selected angle of honing by said honing wheel against said doctor blade.

2. A machine for honing a doctor blade comprising a mounting for a doctor blade to hold said blade in a given position with its axis oriented along a given line, a honing wheel having an axis of notation parallel to said first-mentioned axis, a U-frame having as uprights a pair of bars respectively, bearings art the upper ends of said bars to receive saidhoning wheel, a motor carried by said frame, a cam and follower arrangement, gearing coupled between said motor and said cam and follower arrangement and said honing wheel whereby said Wheel is driven (for rotation about its axis and for reciprocation back and forth in a direction parallel to its axis, a mounting for said U-frame with pins at its respective uprights whereby said frame may be rocked about said pins, and a cam setting for rocking said frame to a desired, selected position, whereby said doctor blade, when in position for honing, is presented to said honing wheel for honing an edge at a desired angle.

3. A machine for honing doctor blades comprising a mounting for said blade, a grinding wheel carried on said machine for traversing along a line parallel to the axis of a doctor blade when mounted in its said mounting, said 7 grinding wheel being adjustable in position toward or away from said doctor blade, a honing wheel, means for mounting said honing Wheel for rotation about an axis parallel to that of said blade when mounted, and means for driving said honing wheel simultaneously for rotation about its axis and for a stroking motion back and forth in a direction parallel to its said axis, said honing wheel mounting means comprising a .U-frame, said doctor blade mounting positioning said doctor blade, when mounted, between said honing wheel and said grinding wheel and further including means for presenting the edge of said doctor blade in turn to said grinding Wheel and to said honing wheel.

4. A machine for honing a doctor blade having a longitudinal axis, comprising a honing wheel having an axis and mounted for rotation about the honing wheel axis, means for rotatably driving said honing wheel and at the same time providing it with a stroking motion in a direction parallel to said axis of rotation, a grinding wheel, means for mounting said grinding wheels for traverse parallel to said axis, and a mounting for mounting said blade between said honing wheel and said grinding wheel and comprising means for selectively presenting, while maintaining said blade axis parallel to said honing wheel axis, the blade edge to said grinding Wheel for grinding and to said honing wheel for honing.

5. A machine as claimed in claim 4, said grinding wheel having an axial length substantially less than that of said honing wheel, and said grinding wheel mounting providing for traverse of said grinding wheel along the entire axial length of said blade.

6. A machine as claimed in claim 4, said grinding Wheel mounting including a means tor advancing said grinding wheel closer to said doctor blade at each said traverse of said grinding wheel.

7. A machine as claimed in claim 4, said grinding Wheel having an axial length substantially less than the axial length of said honing wheel and said grinding wheel mounting means including a means for traverse of said grinding wheel along the entire axial length of said blade and beyond the ends thereof, and means for advancing said grinding wheel closer to said doctor blade at each said traverse.

8. A machine as claimed in claim 4, said grinding wheel axis being canted with respect to the direction of traverse whereby as said grinding wheel traverses, only one edge of said grinding wheel actively is brought to bear against said doctor blade.

9. A machine for honing doctor blades comprising:

a mounting for a doctor blade having a longitudinal axis,

a honing wheel,

means for mounting said honing wheel for rotation about an axis parallel to said first mentioned axis,

means for driving said honing wheel simultaneously for rotation about its axis and for a stroking motion back and forth in a direction parallel to its said axis,

said honing wheel mounting means comprising a frame having upright bars across which upright bars said honing wheel is mounted and means for selectively positioning said bars thereby selectively to position said honing wheel mounted thereon while maintaining said honing wheel axis parallel to said longitudinal doctor blade axis,

said doctor blade mounting being between said wheels and operative selectively to present an edge of said doctor blade for grinding by said grinding Wheel as said grinding wheel traverses and for honing by said honing wheel at an angle dependent on the honing wheel position selected by said selective bar positioning means.

References Cited in the file of this patent UNITED STATES PATENTS 492,451 Winkley Feb. 28, 1893 1,027,045 Hanson May 21, 1912 1,034,422 Christiansen Aug. 6, 191-2 

3. A MACHINE FOR HONING DOCTOR BLADES COMPRISING A MOUNTING FOR SAID BLADE, A GRINDING WHEEL CARRIED ON SAID MACHINE FOR TRANSVERSING ALONG A LINE PARALLEL TO THE AXIS OF A DOCTOR BLADE WHEN MOUNTED IN ITS SAID MOUNTING, SAID GRINDING WHEEL BEING ADJUSTABLE IN POSITION TOWARD OR AWAY FROM SAID DOCTOR BLADE, A HONING WHEEL, MEANS FOR MOUNTING SAID HONING WHEEL FOR ROTATION ABOUT AN AXIS PARALLEL TO THAT OF SAID BLADE WHEN MOUNTED, AND MEANS FOR DRIVING SAID HONING WHEEL SIMULTANEOUSLY FOR ROTATION ABOUT ITS AXIS AND FOR A STROKING MOTION BACK AND FORTH IN A DIRECTION PARALLEL TO ITS SAID AXIS, SAID HONING WHEEL MOUNTING MEANS COMPRISING A U-FRAME, SAID DOCTOR BLADE MOUNTING POSITIONING SAID DOCTOR BLADE, WHEN MOUNTED BETWEEN SAID HONING WHEEL AND SAID GRINDING WHEEL AND FURTHER INCLUDING MEANS FOR PRESENTING THE EDGE OF SAID DOCTOR BLADE IN TURN TO SAID GRINDING WHEEL AND TO SAID HONING WHEEL. 